[Oberon] PNG Encoder codec

[F. Necati Ecevit]

> From the FreeImage documentation: 

> "FreeImage is easy to use, fast, multithreading safe, compatible with
> all 32-bit or 64-bit versions of Windows, and cross-platform (works
> both with Linux and Mac OS X)"

>  could port the PNG module from free pascal. it is just the
> sort of thing he is good at.

I had written the FreeImage.dll wrapper module for BlackBox Component Pascal six years ago.
It can be ported WinAos and LinuxAos; please stay tuned, i will try to do it.

FreeImage is better than libpng as it support more image formats.

- Necati.